We spent a week in Lake Como in May and we were in Bellagio. I'm very happy with our choice. We did several walks to the little villages close by, and the ferry stops by often so it's easy to get across to the villas on the west side, or to Varenna. We had a VRBO that was a good price. We were right across from the church in the centre of town with a little balcony to get the morning sun or afternoon shade, and our front had a French balcony overlooking rooftops and the lake. It was very comfortable, and we were in the centre of things and all on our own at the same time. Bellagio has lots of places to eat, wine bars, and nice small shops (silk scarves are a specialty in the Como area and they're easy to bring home). It gets quiet by late afternoon when the day trippers leave.
I had looked at Varenna but realized there really wasn't enough there for us for a whole week (mostly around getting food--restaurants and grocery shopping). The west side towns are busier, as there is a road that goes up that side of the lake.
We rented bikes up the hill from Bellagio. They had e-assist bikes for me, and they sent us on an epic ride-- ferry across the lake and then up and over a mountain and down to the eastern reach of Lake Lugano, and an valley trail back. It was easy with the e-bike.
As for flying out of Florence, make sure you give yourself lots of time. It's a small airport, but poorly organized, and it has a short runway with weird wind patterns. We recently flew Florence to Munich, which is a flight under an hour. We had an almost 2 hour layover in Munich, but alas due to the chaos at Florence airport and the unpredictable winds (once we finally got on the plane, it was further delayed 45 minutes waiting for the wind to change), we missed our connecting flight to North America. We vowed never to fly out of a small Italian airport again if we need to make a connecting flight (my husband had problems flying out of Pisa in 2017 too). So long connections, if you're making them. Or fly out of Milan maybe (I've never flown out of Milan so can't comment on it either way).